"Influence" vs. "Manipulation"

I suppose, at the very least, if I can't talk about anything of use, I may as well point you in the direction of something, anything, interesting: something I have been reading up a bit more on in what precious little spare time I have is Neuro-Linguistic Programming.  A fast becoming favorite of mine of late, this entire field appears to be nothing more than not-so-thinly-veiled manipulation.  It's a funny to think about, coming up quite a bit in The 7 Habits of Highly Effective People, the subtle, possibly non-existent difference between "motivation", "influence", "manipulation", and "coercion".   Covey, for instance, often speaks of the positive effects of the "influence" the 7 Habits can have over you personally as well as the people around you, but often includes examples that run against a Habit, summing those up as "manipulation", as if the Light Side of the Force puts these into practice in one way while the Dark Side does the same thing, but since their hearts aren't pure, it brings a completely different connotation.  Just the entire concept of "coercion" is hilarious to me - teachers coerce students to do well, using stickers, candy, and positive and negative rewards (a positive reward is offering a good thing, a negative reward would be removing a bad thing - similarly a negative punishment is taking away a good thing and a positive punishment is introducing a bad thing...get it?), but we never call that "coercion".  We've all seen enough bully-prevention shticks to know that "power in numbers" can keep kids safer because bullies probably won't go against a crowd...but explain to me exactly how this is different than controlled peer pressure?  "Don't do it again or I'll call home!", "Watch it or you'll get sent to the principals office!" (alright, these may be a bit outdated but I'm not as hip to the exact lingo anymore) - are these nothing more than intimidation principles?

Now, this isn't by any means a condemnation of any of these things.  I think coercion, manipulation, intimidation, and deception are universal traits found throughout much of human interaction.  I think these are somewhat even necessary for functioning society.  Liminal or subliminal, overt or covert, conscious and intended or unconscious and unintended, these concepts exist all around us, we just have to be aware of how and when we use them and when they're being used on us.